<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            box-sizing: border-box;
            /* width: 200px; */
            /* height: 200px; */
            width: 50vw;
            height: 50vw;
            padding: 20px;
            border: 10px solid red;
            margin: 20px;

        }
    </style>
</head>

<body>
    <div>
        111
    </div>
    <div>
        111
    </div>
</body>

</html>